Book excerpt: This book constitutes the refereed proceedings of the 25th Annual International Cryptology Conference, CRYPTO 2005, held in Santa Barbara, California, USA in August 2005. The 33 revised full papers presented were carefully reviewed and selected from 178 submissions. The papers are organized in topical sections on hash functions, theory, cryptanalysis, zero knowledge, anonymity, privacy, broadcast encryption, human-oriented cryptography, secret sharing, multi-party computation, random oracles, information theoretic security, and primitives and protocols.